Track-circuit system



Sept. 4, 192& 1,683,222

A. G. WILLIAMSON TRACK CIRCUIT SYSTEM Original Filed April 5 1922 2 Sheets-Sheet 1 ATTORNEY A. G. WILLIAMSON TRACK CIRCUIT SYSTEM Sept. 4, I928. 1,683,222

Original Filed April 5. 19 2 2 Sheets-Sheet. 2

Q: INVENTOR A TmRNE Y Patented Sept. 4, 1928.

UNITED STATES.

ABBA G. WILLIAMSON, or CARNEGIE, rE-NNS LV A, ssronon TO PITTSBURGH TRAIN CONTROL COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF DELAWARE.

TRACK-CIRCUIT sYsrEr/r.

'Application filed April 5, 1922, Serial N0. 549,662., Renewed February 3,

This invent-ion relates to track circuit systems particularly for use in connection with train control systems of the type d1sclosed in application Ser. No. 555,304, filed April 18, 1922.

In systems of the character 1nd1cated 1n those applications the train is prov ded w th two picleup circuits one of the ndirect type and the other of the direct type and the main object of this invention is to provide means whereby a circuit may be established including both rails of a block and whereby also another circuit may be established between one or both rails and ground to properly coordinate the indirect and direct pickup circuits on the trainwith track equipment. By indirect pick-up circuit is meant a circuit on the train in inductive relation to the current in the rails and by direct pick-up circuit is meant a circuit on the train of an electrostatic character, that is: there is a device in the trainin circuit with one or more rails and having a capacity between itself and ground.

A further object of the invention is to provide means whereby the circuit between one rail and ground is so arranged that existing track circuits may be used with but slight alteration.

Other features of the invention will appear as the specification proceeds.

The broad features of this invention are claimed in applicationSer. No. 549,661,filed April 5, 1922, one of the specific forms shown in that application being the subject matter of this application. r

In the accompanying drawing the invention is shown diagrammatically in two preferred forms as part of a standard track circuit, Fig. 1 showing the track equipment controlled by the signals and Fig. Qshowing the track equipment. controlled by a relay.

Referring to Fig. 1, 1 and 2 represent the rails of a traflic track divided into blocks, W, X, Y and Z in a manner well understood as-by means of insulation 3. 4 and 5 indicate line wires fed by a single frequency generator G. Associated with each block is a main transformer indicated by T10; T00 and Ty] and the secondary 6 of each of these transformers is connected by means of conductors 7 and 9 with a primary 8 of a track transformer indicated variously as Nw, N00 and Ny. Thus secondary 6 conductor 7, primary 8 and conductor 9 constitute what may be called an intermediate circuit. Secondary 13 of the track transformer isconnected by suitable leads'with rails 1 and 2 thereby supplying ourrent to both ofsaid rails of a given block. lnterposed between secondary v6 of the main transformer and primary 8 of the track transformer is a circuit breaker 1n type being influenced both by the track circu'it and by current from transformer T in a manner to be presently described. Q, in dicat es a winding affecting relay L, this winding being connected to wires 7 and 9 and therefore fed by transformer Ty Accordingly one element of relay L receives current'from the track circuit and theother element Q, from the main transformer. It

is well known that when the instantaneous polarity of both elements is such that the currents in both elements are in phase then arn'iature will swing to right hand position. If the connections of one element should be reversed so that the instantaneous polarity of the currents in the'two elements are out of phase then armature 100 will swing to the left hand position. If current is absent in the track elemontftlich armature 100 will hang in center position, Reversal of the instantaneous polarity of the current in the track rails is accomplished bythe pole changer reversing the connections to the primary of the track transformer, the pole changer being here operated by the si nal mechanism as ind cated by dotted line .t is further wellknown that when signal S2 is a stop or danger position-then pole changer P is moved to the left hand position, in which position -tl1einstantaneous polarity of the current in rails of block Y is out of" phase withthat of element Q1] and armature 1000f relay l g will therefore assume its left hand position and signal Sg ill therefore assume caution position. Signal Sg/ when moving into caution position will move polejchanger Pm from left to right hand position, and thepolarity ofthe current in the rails of block X being now such in respect to element Qw that armature 100 of relay Lav will assume its righthand position and therefore signal Sm'will move to clear. vVhenthis occurs signal Sac will not move pole changerPwq to any new position but said pole changer will occupy the same, position as it did under caution conditions. ,7 Assuming now that a" train proceeds in the direction indicated by the arrow,it will be i j understood that "so long as current is flowing int-hetrackcircuit the indirect pick up cir cuit on the train will be influenced and it i is only when a train enters a'blook suchas Z, already. foccupiedby another train, that the indirect pick-up circuit is'not influenced by the track circuit. When a train K occupies block Z then pole changer Pwwilloccupy its-right hand position and-currentfrom secondary '6 of transforinerfTaz will be supplied to the rail and ground circuit as follows: secondary 6, conductor] 7, conductor 101, impedance 102,

conductor 103, ground 104:, rail 1, conductor 14, shunt 105, conductor 7 polechanger Pas,

conductor 9, and back tosecondary 6. Rail 1 is not grounded but may in factbe insulated from ground; Thatis to say the insulation is of course not perfect and there exists a leakage of currentbut not excessive so that voltageaboveground potential is maintained on the rail. If the rail was actually grounded it would not be possible to maintain this voltage and consequently the direct pick-up circuit wouldnot receive an impulse; The direct pick-up circuit of a train entering block X willtherefore be influenced." In block Y, however, pole' changer Py'isin the left hand position and therefore that side of secondary 6 of trans- ;formei' Ty which is connected to ground is also connected to rail lof block Y and there-- fore no current from secondary 6 flows through the rail and ground circuit. Therefore the dialect. pick-up circuit ofthe train will not beinfluenced. V

In Fig.2 the signal control is omitted and a an additional relay 150 is interposed which relay controls the pole changer, andis controlled by armature 100. Relay 150is energizedrby connecting one wire 151 to Wire- 9, connecting armature v100 to Wire 7 of the intermediate circuit and providing two contacts 152 and 153c0nnected to relay 150.- It will be seen that when relay L2 is deenergized its armature 100 will drop thereby rupturing circuit through relay 150a and causing current of onepolarity to be sup- 'pliedto the track transformer by means of pole changer Pg and also cutting out the rail and groundicircuit. This energizes relay Lg causing its armature to swing to the left into engagement with 152 thereby estabi,ess,22a V lisliing a circuitthrough relay 150g and W and maintaining th rail and ground Gib cuit intact. p c

The arrangement shown in'Figure 2 ofthe drawings hereof is not claimed specifically in causing pole changer fPaa to supply current of the opposite polarity to track traiisform-' er N 00 and at the same time establishing the rail and ground circuit; This :inturn energizes-relay Lm to move its armature 100 to the right against-contact 153 thereby sup plying-current of thesame-polarity to block the present application, butforms the subject 16,1928, Sci. No; 299,885.

Iclaim: I

, 1. A track circuit system comprising:

traffic rails divided into blocks, a circuit inmatter of another application filed August clu'dingboth rails of a block, a circuit be tween ground and at least one of sai'djrails for 'niain'taining voltage above ground pa;

tential on at least one'of saidrails, and a 7 pole changer controlled from a "preceding block and controllinglfboth circuits of the local block. I I

2. A track circuit system comprising trafficfrails divided into' blocks, a circuit in- 3.-A track circuit. system comprising traffic rails divided into blocks, a track cirit cuit includingboth railsof a bl0ck,, an intermediate circuit, a main circu t, a transformernbetween the main and intermediate circuits, :1. trackfltran'sformer between, the

intermediate and ,track circuit, a "pole changer in the"intermedfiate c rcuit, a shunt around the track transformer and connecting the intermediate and track circuits, "and a ground connection 'in the intermediate circuit between the transformer. r Y a V a 4. A track circuit system comprising: traflic rails dividediinto blocks, a track circuit including both rails of a block, an intermediate circuit, a main circuit, a trans former between the main and intermediate vcircuits, a track transformer between the intermediate and track circuits, a pole changer in the intermediate'circuiu a shunt around the track transformer and connecting the intermediate and track circuits, aground connection in the intermediate circuit be? tweenithepolechanger and the main transv.

former, and. a twoelement relay, one element of which is included intl e track circuit and the other element ofwhich is controlled from the main transformer of a succeeding block.

pole changer and the main 5.VA track circuit system comprising:

trafiic rails divided into blocks, a track circuit including both rails of a block, an in-,

termediate circuit, a main circuit, a transformer between the main and intermediate circuits, a track transformer between the intermediate and track circuits, a shunt around the track transformer and connecting the intermediate and track circuits, a ground connection in the intermediate circuit, and a pole changer controlling the polarity of the track circuit and acting to include or exclude the main transformer between the shunt and the ground connection.

6. A track circuit system comprising: trafiic rails divided into blocks, a track circuit including both rails of a block, an intermediate circuit, a main circuit, a transformer between the main and intermediate circuits, a track transformer between the intermediate and track circuits, a shunt around the track transformer and connecting the intermediate and track circuits, a ground connection in the intermediate circuit, a two element relay one element of which is included in the track circuit and the other element of which is controlled from the main transformer of'a succeeding block, a pole changer controlling the polarity of the track circuit and thereby the two element relay of a local block and acting also to include or exclude the-main transformer between the shunt and the ground connection, said pole changer being controlled from the two element relay of a preceding block.

Signed at Pittsburgh, in the county of Allegheny and State of Pennsylvania this 30th day of March 1922.

ABBA G. WILLIAMSON. 

